There are a variety of techniques that had been proposed for decontaminating a hydrocarbon contaminated, permeable subterranean earth formation. One technique, for example, for treating such an earth formation is to flood the formation with dilute solution of a surfactant. This technique is known as surfactant flooding. Surfactant flooding, however, suffers from the disadvantage that the surfactant fluid either "fingers" through or "by-passes" the contaminant limiting the effectiveness of the process.
U.S. Pat. No. 5,008,019 discloses the use of a polymer in an aqueous flooding solution to control the mobility of the solution injected into an earth formation. The amount of mobility control provided by typical aqueous polymer solutions, however, tends to be very limited because, the range of viscosity that can be achieved by adding a polymer to an aqueous solution generally is relatively narrow. In theory, the efficiency of surfactant flooding processes would be increased if the viscosity of the surfactant fluid is at least substantially equal to or greater than that of the viscosity of the contaminant trapped in the formation.
It is an aim of the present invention, therefore, to improve surfactant flooding processes by providing an aqueous solution of a polymer and one or more surfactants in which the polymers and surfactants are capable of being combined in various concentrations that will provide a wide range of viscosities thereby permitting closer tailoring of the viscosity of the surfactant solution for the hydrocarbon contaminated earthen formation to be decontaminated by flooding.